Meteorite Impact in Virginia
School blocks YouTube?
Intro to Gravity
St. Mary's Physics
Illustration from Newton's
Principia
- Cannon on a Mountain
I. Satellite Motion
Satellite - smaller body revolving around a larger body
Natural Satellites
ex) Moon, all 8 planets, comet
Artificial Satellites
- weather, spy, communications
See where
the earth's
satellites are right now!
Click this link and wait until
the program jumps to the screen.
A. Satellite Motion
1. To send artificial satellite in circular orbit around earth it must first achieve a speed of 7900 m/s
If greater than 7900 m/s satellite has an elliptical orbit
If velocity is greater than 11 km/s then satellite leaves earth's orbit (called escape velocity)
2. Air resistance slows down satellites and eventually causes them to spiral back to earth.
Peekskill Fireball
Meteorite Peekskill, Ct. (NASA)
Winslow, Arizona
Crater created when a 50-meter-wide (160-foot-wide)
iron-rich
meteoroid struck the Earth's surface about 50,000 years ago
David Roddy, USGS.
Why does the moon have so many craters
compared to
the earth?
The moon has very little erosion.
"On Earth, impact craters are harder to recognize because of weathering and erosion of its surface. The Moon lacks water, an atmosphere, and tectonic activity, three forces that erode Earth's surface and erase all but the most recent impacts. Approximately 80% of Earth's surface is less than 200 million years old, while over 99% of the Moon's surface is more than 3 billion years old. Essentially, the Moon's surface has not been modified since early in its history, so most of its craters are still visible."
B. Geosynchronous Orbits
1. When a satellite orbits in time with earth’s rotation it is called geosynchronous.
2. Time for
one revolution - 24 hrs
3. A satellite at distance of 6 earth radii from earth's center will orbit earth every 24 hrs.
4. Since both satellite and earth move together, it always remains directly above same spot above earth’s equator.
Learn more about Circular Motion at
Georgia Public Broadcasting
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